The metabolites formed from benzo(a)pyrene, benzo(a)anthracene and 3-methyl-cholanthrene by the filamentous fungus, Cunnighamella elegans, will be isolated and identified. Special attention will be paid to the enantiomeric specificity shown in the formation of trans-dihydrodiols. Attempts will be made to purify and characterize the following enzymes from this microorganism: cytochrome P-450, epoxide hydrase, cytochrome c reductase and glutathione transferase(s).